FLOOD04661

• County: Boulder
• Community: Boulder
• Stream Name: South Boulder Creek
• Basin: South Platte
• Title: Floodplain Analyses of South Boulder Creek at Flatiron Property
• Date: 8/12/1996
• Prepared For: University of Colorado at Boulder
• Prepared By: Love & Associates, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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return to its floodplain. The current G&O study incorrectly states that
approximately 1,660 cfs spills to the north and rejoins the South Boulder Creek
main channel floodplain downstream of US Highway 36.

4. Since 1973 when the R.W. Beck study was published, it was identified that
properties in the Keewayden Meadows neighborhood and other properties to the
north of US 36 are at risk from flooding of South Boulder Creek. The split flows
in South Boulder Creek existed prior to the mining of the Flatiron property due to
the construction of the elevated section of U.S. Highway 36 which was built in
the late 1950' s.

5. If a FEMA certified flood protection levee is completed on the Flatiron Property,
the neighborhoods to the north of U.S. 36 would be in less of a flood hazard than
without the levee in place. Additionally, the levee will serve to keep the majority
of the Flatiron Property out of the South Boulder Creek lOO-year floodplain.
Under Condition 1, loo-Year Floodplain Model- No Levee with 200-Foot Wide
Channel approximately 113 acres or 37% of the property is within the floodplain.
Ten of these 113 acres would be in a shallow flooded condition and could be
removed with minor modifications to the interceptor channel. Under Condition
2, 100- Year Floodplain Model - FEMA Certified Flood Protection Levee, 82
acres or 27% of the property would be located within the South Boulder Creek
floodplain. In neither condition is a majority of the Flatiron Property in the South
Boulder Creek floodplain.

RECOMMENDATIONS

Based upon the fmdings of the hydraulic analyses of the South Boulder Creek loo-year
floodplain in the vicinity of the Flatiron Property it is our professional opinion that it
would be in the best interests of all parties to have the berm on the Flatiron Property
certified as a FEMA approved flood protection levee. The certification process is very
extensive in its requirements. Numerous engineering tests and calculations will be

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